Advanced Treatment of Recalcitrant Textile Wastewater and Goal-oriented Process Design

摘要

This study was intended to evaluate the performance of a biological and a chemical treatment process of recalcitrant textile wastewater. The biological process consisted of Activated Sludge (AS) reactor followed by column reactor packed with cell-immobilized pellets. The chemical process consisted of coagulation/precipitation and ozone oxidation. Experiments were conducted by pilot-scale reactors fed with textile wastewater. The removal efficiency of BOD by AS process was 85%, but only 45% of the COD was removed, indicating the AS process was not satisfactory in removing recalcitrant organic matter. However, the packed-bed column reactor effectively removed the recalcitrant organic matter, showing stable performance at an empty bed contact time of 8 hours. Both PAC and ferric chloride appeared to be excellent coagulants for removal of the remained hardly-biodegradable COD. Although the previous biological processes and coagulation/precipitation had already removed 74% of the color in the influent, most of the remaining color was removed by ozone oxidation at a contact time of 20 minute. A combination of AS, PEG-pellet column, and coagulation/precipitation produced a good effluent quality which met the discharge standards of most Asian countries. Additionally, if the ozone oxidation was added, the effluent quality could meet more stringent standards of advanced countries.